I've had good luck with POR-15 engine enamels. Just like every painting job, proper prep is of key importance.
I don't think PJ-1 engine paints are around anymore...they were good too.
RIcklessssssS in Oregon

No worries.....prep well and paint away. Did that so many years ago well before the Internet and so many choices of Hi-temp paints.Good old Tremclad Hi-Heat, been around for a long time that one. But for little touch ups I could do with a little paint brush it lasted very well.

Aluminium....hard to prep so porous in places. Good for paint adhesion but not so if you want to get rid of corrosion first. May require blasting with the right media.

There are proper primers for Aluminium such as Zinc Chromates but I only use them for touch ups where corrosion was present at first. Not a clue as to their heat specs but I did some on my engine right next to the exhausts, 1' or 2" no water cooling there, and finished with Tremclad Hi-heat, all still there after 3 years.

Nasty fumes them Zinc primers....read the warnings if you choose to use them.

I've had good luck with POR-15 engine enamels. Just like every painting job, proper prep is of key importance.
I don't think PJ-1 engine paints are around anymore...they were good too.
RIcklessssssS in Oregon